Sine and cosine
The sine and cosine are the basic trigonometric functions.
The sine is positive in the first and second quadrant
The cosine is positive in the first and fourth quadrant
We'll assume the angle is in the first quadrant, so the cosine and the sine are positive
The basic identity that relates the sine and the cosine of a given angle is:
If we are given the sine of the angle:
The cosine can be calculated by solving the above identity for the cosine:
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